VCF some basics questions

[zeeshan qadir]

Hi everyone,

I am new to VCF things, I have some basics questions:

1)  Let's say we have single VCF region, with one management domain, and one Work load domain WLD1.

WLD1 has its own NSX mangers, and own Vcenter.

Let's say we want to create another work load domain WLD2, can we use the Vcenter and NSX mangers from WLD1 for WLD2?

2)  Let's say we have WLD1, this WLD1 has two clusters:  NY-Cluster, and CA-Cluster.  NY cluster has esxi hosts at NY location, and CA-Cluster has eSXI hosts in CA location.  I was told, a WLD can not have two different clusters at two different location because of latency which I believe is not true.

NY-Cluster has hosts which are same location at NY. similarly, CA-cluster has esxi hosts at same CA location.

So I do not understand why we can not have WLD with two clusters at two different locations.

Much appreciated!!

[Jean-Claude Daunois]

Hi, 

each new WKL Domain will create a new vCenter Server.

for NSX, you will have the choice during creation. You can attach the new WKL Domain to the existing NSX Manager, or you can create a new one. 

nsx can't be merge between admin et production wkl domain, meaning creation of the first wkl domain will always create an NSX manager.

Yes, it is not supported to have 2 location too far in the same wkl domain. You have to look at multi region design for such distance.

You habe to keep in mind that cluster are manager by VC and NSX Manager which are running in admin wkl domain, and this one will  be in one site only. 

so having a cluster in CA while admin is in NY will have too much latence, and more problematic, will have too much risks around network link problem.

so if you want to do that, you have to follow the multi region design. 

by default VCF is single region, meaning you must stay in same location or close enough to have network spread everywhere and low latency. 

multi region design is quite different.. 

[Doug Baer]

It is my understanding that you can share an NSX Manager instance between multiple VI workload domains by setting it as shared when you create a new domain. However, you cannot share an NSX Manager instance between a VI workload domain and the management domain. Look at the bottom of this document (VCF 4.5, but I think it remains the same) for some details
Logical Design for NSX-T Data Center for a Virtual Infrastructure Workload Domain

Regarding your question about a single workload domain with clusters located at different sites, you can consider "it depends," as the real answer: Is it technically possible to set it up, I believe so. It it a good idea? That depends.  Latency is definitely one concern. 

This link covers the "remote cluster" configuration in VCF 5.1+ and states the minimum bandwidth of 10Mbps and max latency of 100ms - https://docs.vmware.com/en/VMware-Cloud-Foundation/5.1/vcf-admin/GUID-BE31158E-8FC1-48EE-99DF-2B2CDA7B9B24.html

I am not aware of a limitation that would prevent a single WLD hosting two separate clusters at separate locations, as long as those locations both meet the connectivity requirements back to the vCenter and SDDC Manager. 

My question would be about the reason for this configuration.  What are you hoping to achieve by managing both clusters with the same vCenter?  Looking at those reasons and understanding whether the remoteness of the clusters will permit achieving those goals is where I would start.

This is an older document, but it looks at some performance implications of ESXi hosts placed at distance from the managing vCenter
https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/techpaper/performance/robo-vcenter67-perf.pdf

I hope that helps, 

Doug

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Advanced Services Architect | VCF Division
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